Abstract We have studied the transport property of the composites (La0.83Sr0.17 MnO3)1-x(ITO)x [ITO=(In2O3)0.95 (SnO2)0.05], which were fabricated by mechanically mixing La0.83Sr0.17 MnO3 and ITO grains. A giant positive magnetoresistance (PMR) has been observed above the Curie temperature Tc for samples with x around 0.40, in addition to the negative magnetoresistance related to spin-dependent interfacial tunnelling below Tc. For (La0.83Sr0.17MnO3)0.6(ITO)0.4, the magnetoresistive ratio for the PMR can reach 39.3% under a magnetic field $H=2.24\times10^5$A/m. Theoretical analysis suggests that the magnetic-field-induced broadening of the p--n barrier between both kinds of grains and the density of the p--n heterostructures should be responsible for the PMR behaviour.
Received: 17 December 2005
Revised: 25 January 2006
Accepted manuscript online:
(Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.))
Fund: Project supported by the National Natural Science Foundation of China (Grant No 20473038), the Foundation of High-Tech Project in Jiangsu province, China (Grant No BG-2005401).
Cite this article:
Wang Miao (王淼), Zhang Ning (张宁) Simultaneous observation of positive and negative giant magnetoresistances in composite (La0.83Sr0.17MnO3)1－x(ITO)x 2006 Chinese Physics 15 850
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